From your description I assume that you were asking for a rain cape. You either asked for a certain rain cape or you assumed, while the saleswoman was searching, that the shop the rain capes were out of stock.

In this case auch is correct.

The saleswomen expressed that they have that item of clothing in stock (among others, also).

The word doch would be correct if you have had (in a disappointed way) implied that they're out of stock: